doctors desk examining risks of medically induced coma

The Risks of a Medically Induced Coma

While a coma is the inadvertent entering of a prolonged state of unconsciousness, a medically induced coma is the entering of that state intentionally. In most cases, the goal is to allow the brain to heal and recover by slowing down its activity. It is generally reserved as a last resort treatment. Unfortunately, it does not come without risks of its own. 

What is a medically induced coma?

A doctor or anesthesiologist uses specific medications to put a patient into a coma. The fundamental difference (beyond intent) is that a medically induced coma is reversible. Anesthetics, barbiturates, or occasionally benzodiazepines are the most commonly used drugs for medically induced comas. When the cause of the coma is a traumatic brain injury, issues like swelling and bleeding can be extremely dangerous. There is only so much room in your head for your brain to expand, and so eventually it can put pressure on already injured parts of the brain or on the brainstem that controls fundamental reflexes, like blinking and breathing patterns. Furthermore, this swelling can inhibit blood flow, and when the brain doesn’t get enough blood, it doesn’t get enough oxygen, and it starts to die. 

Inducing a coma makes it so the brain doesn’t use -- and therefore doesn’t need -- as much energy, and can take time to heal and allow the swelling to reduce. Additionally, a coma induced through hypothermia has been used to perform heart surgeries, slowing down blood flow to prevent blood loss. This may go on for as little as a day or, in one extreme case, as long as six months. 

What are the risks during a medically induced coma?

Admittedly, anesthetics are used for surgeries by the thousands every day. In most cases, however, the drugs aren’t given until brainwaves start to slow. In an interview with Scientific American, Harvard Medical School’s anesthesiologist Emery Brown explains that one of the main risks of a medically induced coma is low blood pressure. This means a lot of other medications are necessary to keep the blood pressure high enough and the blood pumping appropriately for the brain and the rest of the body to remain alive. The heart can grow weak, blood doesn’t circulate the way it needs too, and ultimately, heart failure can result. 

Additionally, since these medications can be used for quite some time, the drugs can stay in the system for a while. The patient’s immune system can also become impaired, making someone who is already a health risk more likely to develop dangerous infections. If someone with a perfectly healthy brain was being put into a medically induced coma, it might be a simple matter of waking them up after a few hours -- but medically induced comas aren’t being used on people with perfectly healthy brains. Although the goal of the coma is to protect the brain, there’s always the chance that this won’t work and that either the medically induced coma can become more permanent than intended, or when it is reversed, the brain hasn’t healed the way it was hoped to, resulting in a persistent vegetative state. 

Last Updated: October 06, 2016